A common type of demountable building is one having a plurality of arc frames disposed in vertical planes extending traversely of the building and spaced apart longitudinally of the building, each arc frame being mounted on the ground or on a ground support so as to be movable during assembly longitudinally of the building by adjustable spreader devices acting between pairs of neighboring arc frames. In this manner, fabric membranes held between the pairs can be tensioned.
One of the first patents issued for the above-mentioned type of building was Canadian Patent 937,479 of Sprung issued Nov. 27, 1973. The patent disclosed a building structure having a plurality of vertically erected, parallel, longitudinally spaced arc frames that rose from a wide base to a peak. The arc frames were originally made of laminated wooden beams, but subsequently they were made of aluminum I-beams. Coated nylon membrane coverings consisting of elongated strips were laid between adjacent arc frames, the opposite sides being thickened to provide a bead-like edge for clamping attachment to the outside of the arc frames on either side. After the membrane coverings were clamped to the spaced arc frames, in a relatively slack condition, the arc frames were spread to tension the respective membrane coverings by the use of a spreader. Canadian Patent No. 1,059,871 of Sprung issued Aug. 7, 1979, described and illustrated and improved constructions of such a building structure.
U.S. Pat. No. 4,229,914 of Lucas issued Oct. 28, 1980 discloses a building structure including a plurality of arc frames in vertical planes. Each of the arc frames has a plurality of mutually inclined straight parts of generally I-beam cross-section. The arc frames are retained in their fixed position by horizontal bracing struts consisting of square cross-section tubes. Beading of the elongate strips for the building permits attachment to the arches.
U.S. Pat. No. 5,181,352 of Friedman issued Jan. 26, 1993 discloses a rain cap system for assembly junctions of a stressed membrane structure. The arches illustrated in the patent each include a plurality of hollow extruded box-beam segments. The box-beam segments are formed with pairs of longitudinally extending, outwardly opening, rope chases on opposite sides thereof. An aluminum rain cap is conformed to cover the junction of box-beam segments. The cap is held in place by the spring tension of the metal cap, which allows it to grip the box-beam segment by means of two lips.
Previously rope chases for the beams used in the arc frames were welded or bolted onto the beam. The arc frame spacing associated with these types of beams was small, for example, only slightly more than 5 feet on center.
A known method of insulating such demountable structures includes the installation of foil back bubble wrap with 1″ thick ducting insulation. This provides poor insulation.
The preferred known method for installing the membrane cover for such demountable structures involves inserting the membranes downwardly from the peak of the structure. Problems associated with this method include the need for lifts to move assembly workers to the peak, increased assembly time, and increased danger to the assembly workers.